.image-viewer {
    margin: auto;
    background: #333;
    position: relative;
}
.image-viewer>.controller {
    position: absolute;
    bottom: 0;
    left: 0;
    right: 0;
    margin: auto;
    z-index: 1;
    -webkit-transform: translateY(100%);
       -moz-transform: translateY(100%);
        -ms-transform: translateY(100%);
         -o-transform: translateY(100%);
            transform: translateY(100%);
}
.image-viewer>.view-area {
    outline: 1px solid orange;
    overflow: hidden;
    z-index: 0;
}

.image-viewer-item {
    -webkit-transition: all .5s ease;
       -moz-transition: all .5s ease;
        -ms-transition: all .5s ease;
         -o-transition: all .5s ease;
            transition: all .5s ease;
    position: absolute;
    top: 0;
    left: 0;
}

.image-viewer-enter {
    opacity: 0;
}

.image-viewer-leave-to {
    opacity: 0;
}